Dry cell



C. W. HAZELETT.

DRY CELL.

APPLICATION HLED MAY 9, 1919.

1,831,761 Patented Feb. 1920;

Lvl-vzivro/e ELWHAZ B LE T T I UNITED STATES PATENT OFFICE.

CLARENCE W. HAZELETT, 01? LAKEWOOD, OHIO, ASSIGNOR TO NATIONAL CARBON COMPANY, INC., A CORPORATION OF NEW YORK.

DRY CELL.

Specification of Letters Patent.

Patented Feb. 24, 1920.

Application filed Kay 9, 1919. Serial No. 295,987.

To all whom it may concern:

'Be it known that I, CLARENCE V. HAZE- LETT, a citizen of the United States, residing at Lakewood, in the county ofCuyahoga and State of Ohio, have invented a certain new the can, sothat it may be folded over or otherwise crumpled into position on top of the mix. To complete the cell a layer of sand is usually added on top of the foldedover portion of the linin and then a seal 7,

as molten pitch, is poure on top of the sand until it is substantially level with the top of the can. With dry cells made as specified it is found that there is considerable trouble experienced through the corrosion of the zinc immediately below the layer of sand. The corrosion at this point is much more rapid than in other portions of the cell, and frequently the top portion of the zinc will be entirely separated from the lower portion before the useful life of the cell would otherwise have terminated.

It has been found that the excessive corrosion of the zinc near the top is caused by the greater concentration of electrolyte in this neighborhood, due to the increased amount of electrolyte in the crumpled-over portion of the lining. During the action of the cell the surface of the paper-lining adj acent the zinc is depleted of electrolyte and this must be supplied by the difiusion of other electrolyte from the interior portion of the lining and from the. adjacent mix.

Since there is a greater mass of the paper;

lining at the top due to the crumpled-over portion, the electrolyte will difiuse more rapidly to raise the concentration of the electrolyte in the surface adjacent the zinc, than it will in the lower portions of the lining where there is only one thickness of lining. Consequently there results a higher concentration of electrolyte adjacent the surface of the zinc where the lining is folded over the top of the mix. The difference in concentration between the top of the zinc and the other portions causes continual electrolytic action that eventually dissolves away the zinc at the top.

It has also been found that the excessive corrosion near the top is caused in art by the good conducting path between the electrode and the zinc furnished by the bentover portion of the lining which of course is more or less saturated with good .con ducting electrolyte.

My improvement aims to overcome this disadvantage and the manner in which this is accomplished will now be described, reference being had to the drawings in which:

Figure 1 illustrates a dry cell having the improvement.

Fig. 2 shows a modified method of applying the invention.

The upper cnds of the zinc cans 1 are coated at 2 for a portion of the way down, with some insulating and impervious material, such as the various liquid celluloid compounds or celluloid cements, pitch, tar, etc. The coating may be applied" by means of a brush or the can maybe inverted and dipped in the coating solution and held referably in the inverted position until t e cement or other coating dries. If the can is dipped as specified there will be a coating on the outslde, but this will not be objectionable as it will be covered by the-usual paper jacket. How'- ever, if desired, the coating may be removed as soon as the can is taken out of the solution, by wiping it off.

The coating 2may be applied to the can 1 either before orafter the mix 3 is tamped inside the bibulous lining 4 within the zinc can. Preferably it is applied before the tampin process is applied to the cell. In the cel shown in the drawings the usual layer 5, of sand or other suitable material is placed on top of thebent-over portion 6 of the lining, and the usual seal 7 is added to this. There, of course, will be a suitable binding post attached to the zinc 1, but this has not been shown so as to make clear the invention which involves. the use of the coating material near the top of the zinc. In Fig. 2 I have shown a coating 8 applied near the top of the can on the inside by means of a suitable brush- When the top of the zinc is coated with the insulating and impervious material as specified, the zinc is protected from corrosion ad- 'acent the folded-over portion of the lining, ecause the insulated coating extends below 5 such portion. This increases the path of the current and of the electrolyte sufliciently to very materially reduce corrosion at this point.

While I have described more or less 896- ,10 cifically my improvement, it will be understood that this is 'b way of example and that various modi cations may be made without departing from the spirit of the invention. I

Having described my invention, what I claim is:

1. In dry cells, a zinc' can, an electrolyte mix in said can, a bibulous lining between tion of the lining whereby corrosion is reduced thereat.

2. In dry cells, a zinc can, an electrolyte mix in said can, a bibulous linin between the mix and the can, said lining bemg folded over the top of the mix, a coating of impervious non-conducting material secured to the can and extending substantially below the folded over portion of the lining where- ;by corrosion is reduced thereat.

In testimony whereof, I hereunto aflix m 1 signature. 3 C. W. HAZELETT. 

